This invention relates to a supporting bar of a heddle frame including a frame stave and a heddle carrying rod mounted thereto.
The supporting bars of most of the presently employed heddle frames of textile machines, of which two respective ones are interconnected by lateral supports and form a frame termed heddle frame, comprise a hollow profile of light metal. According to a preferred design the heddle carrying rod is integrally mounted to the hollow profile of the frame stave, having a hollow rectangular cross-sectional profile, via an extended side wall of this hollow profile. The accordingly integral supporting bar may be produced as a drawn profile.
Presently, the longer the broader weaving machines are produced and due to technical improvements the speed of weaving machines is increased continuously such that the heddle frames which are reciprocatingly moved are subject to extremly high loadings. In order to guarantee the necessary bending resistance of the supporting bars it is accordingly necessary to select for the highly loaded heddle frames either a corresponding larger wall thickness or section, respectively for the hollow profile which leads to an increase of the weight and accordingly to an increase of the driving power, or it will be necessary to search for a different compromised solution and e.g. stiffen the light metal profile by steel inserts. Accordingly, it is known for instance to provide recesses in the edges of the light metal forming the hollow body and to insert stiffening rails of steel thereinto.
The steady increase of the loading of the heddle frames of modern weaving machines, specifically at the high speeds, necessitates, however, to account for the alternating bending strength of the material used for the heddle frames. For light metal, this alternating bending strength, drawn as a curve over a number of cycles of stress, decreases initially steeply down to a certain value and thereafter less steep, but still continuously, which does not occur for steel after reaching a certain limit value, such that for light metal due to the steadily declining curve at any given time the breakage due to increased loading can occur. This detrimentally influence the life time of the heddle frame. With regard to the alternating bending strength steel has a much better performance, however this material incorporates a high density which is a drawback for the object at hand.